Hydrangea weberbaueri
Matapalo sprawling hydrangea
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Introduction
Matapalo sprawling hydrangea is a functionally dioecious woody root-climber of the northern and central Andes, distributed from Colombia through Ecuador into Peru. It inhabits tropical rainforest and mountain cloud forest over an extraordinary elevational range of roughly 974–3,500 m and can climb to about 20 m. Its broad distribution once made it easy to subsume beneath H. peruviana, but its leaves reveal one of the most distinctive venation patterns in the entire complex (Samain et al. 2021).
The blades are ovate to lanceolate, generally 13–21 cm long, with weakly glandular-toothed margins. The key character is the organization of the veins: the major lateral veins and intervening secondary veins run in a conspicuously regular, almost parallel pattern before arching together toward the leaf apex. The effect is sufficiently unusual that the 2021 revision used it to identify even somewhat divergent Colombian material as H. weberbaueri. Young surfaces may carry white stellate hairs, while flowering axes can become essentially glabrous or bear only simple pale hairs (Samain et al. 2021; Sutton 2025).
Its nomenclature also required detective work. The original Weberbauer type at Berlin was destroyed, and the surviving fragment elsewhere lacks enough of the distinctive leaf characters for confident application of the name. Samain et al. therefore designated an epitype from near the original type locality in northern Peru. Disturbingly, satellite imagery later showed that the forest where this modern epitype was collected had been destroyed for land-use change within fewer than five years of the researchers' visit. The very specimen needed to stabilize the species name therefore documents a habitat that disappeared almost immediately afterward (Samain et al. 2021).
The current circumscription may not be final. The main distribution appears continuous from northern Ecuador into northern Peru, with additional records farther south in Peru and northeastward in Colombia. Colombian plants show somewhat different venation from the core Ecuadorian–Peruvian material, and the revisers explicitly suggested that future Colombian work could reveal a distinct species. Tree TSAR consequently accepts H. weberbaueri in this broad sense provisionally rather than pretending that all geographic variation has already been resolved.
The nuclear phylogeny reinforces the need for scrutiny. Hydrangea weberbaueri occurs in Clade H, but its accessions do not form one perfectly isolated lineage: several cluster together, while others occur alongside H. albostellata, an unnamed H. sp. 1, and the H. trianae–goudotii complex. One accession even changed strongly supported position between the TIF3H1 gene tree and the combined analysis. This could reflect incomplete sorting, introgression, hidden taxonomic diversity, or some combination (Granados Mendoza et al. 2021).
Horticultural and Agricultural Uses
Hydrangea weberbaueri is unique within this revision complex in having a documented local utilitarian use. An Ecuadorian herbarium collection records the Spanish vernacular bejuco matapalo and the Quichua name yura huanutic caspic, together with use of the plant as fuel wood. It was the only one of the nine species for which the 2021 revisers found a specimen-label vernacular name and explicit human use (Samain et al. 2021).
The name matapalo is especially evocative. Literally associated with tree-clinging or “tree-killing” plants in much of tropical America, it reflects the conspicuous liana architecture rather than evidence that H. weberbaueri parasitizes its host. Cornidia climbs by adventitious roots and remains physiologically rooted in the ground; the revision authors explicitly rejected older descriptions of these hydrangeas as parasitic or hemiepiphytic shrubs or trees (Samain et al. 2021).
No substantial ornamental tradition is documented, but the highly regular venation makes it an unusually handsome foliage plant. Its huge elevational range also makes provenance especially important for any cultivation trial.
Conservation Concerns
The geographic range is enormous on paper: the revision calculated an extent of occurrence approaching 660,000 km². Yet the estimated area actually occupied was only about 224 km², and severe forest destruction and fragmentation led Samain et al. (2021) to assess H. weberbaueri as Endangered under IUCN criteria.
The loss of the epitype forest soon after its collection is a particularly concrete illustration of that threat. In this case, habitat destruction is not an abstract projection derived from distribution modeling; it happened at a documented site central to the modern interpretation of the species.
Taxonomic structure could further increase its conservation significance. If Colombian populations eventually prove specifically distinct, the present broad range will resolve into at least two smaller evolutionary units. Range-wide genomic sampling should therefore be accompanied by provenance-based conservation collection rather than postponed until nomenclature is perfect.
Additional Information
- Open-access 2021 Hydrangea weberbaueri treatment (opens in a new tab): — particularly valuable for the epitype history, vernacular names, fuel-wood use, and geographic variation.
- 2021 Cornidia molecular phylogeny (opens in a new tab): — documents the complex placement of H. weberbaueri accessions within Clade H.
References and Further Reading
Granados Mendoza C, Martínez Salas EM, Goetghebeur P, Wanke S, Samain M-S (2021) Molecular phylogeny, character evolution, and biogeography of Hydrangea section Cornidia, Hydrangeaceae. Frontiers in Plant Science 12: 661522. https://doi.org/10.3389/fpls.2021.661522 (opens in a new tab)
Samain M-S, Granados Mendoza C, Martínez Salas EM (2021) On Hydrangea peruviana, an endangered species from Ecuador, and Hydrangea oerstedii, very common in Costa Rica and Panama, and seven threatened Central and South American hydrangeas, which have been confounded with these. PhytoKeys 171: 91–153. https://doi.org/10.3897/phytokeys.171.56351 (opens in a new tab)
Samain MS, Martínez Salas EM (2015) Hydrangea hunting in the Neotropics. The Plantsman, New Series 14(1): 30–35. https://www.researchgate.net/publication/273124588_Hydrangea_hunting_in_the_Neotropics (opens in a new tab)
Sutton J (2025) Hydrangea species of Section Cornidia. Trees and Shrubs Online. International Dendrology Society. https://www.treesandshrubsonline.org/articles/hydrangea/hydrangea-species-of-section-cornidia/ (opens in a new tab)